The present invention relates generally to a superconductive magnet cooled through solid conduction by a cryocooler coldhead, and more particularly to such a magnet having a support structure which is resistant to shock and vibration forces.
Superconducting magnets include superconductive coils which generate uniform and high strength magnetic fields. Superconducting magnets include those used in magnetic resonance imaging (MRI) systems employed in the field of medical diagnostics. Known techniques for cooling a superconductive magnet include those in which the superconductive coil is cooled through solid conduction by a cryocooler coldhead.
Known magnets include those in which the superconductive coil is surrounded with a spaced-apart thermal shield which is surrounded with a spaced-apart vacuum enclosure. The first stage of the cryocooler coldhead is in solid-conductive thermal contact with the thermal shield, and the second stage of the cryocooler coldhead is in solid-conductive thermal contact with the superconductive coil. Thermal insulating tubes, typically made of radial filamentary carbon graphite, position the thermal shield with respect to the superconductive coil. Racetrack-shaped tie rod straps, typically made of filamentary glass or carbon graphite, support the superconductive coil from the vacuum enclosure. In an alternate known support system, the superconductive coil is vertically supported by a "bar-stool" pedestal stand which provides no horizontal support.
Superconductive magnets are sometimes subject to shock and vibration forces. For example, an MRI magnet is susceptible to shock and vibration forces during shipping and installation, and a naval magnet is susceptible to shock and vibration forces while in use during mine-sweeping operations. Shock and vibration forces during shipping and installation subject the superconductive coil to deflections within the vacuum enclosure leading to frictional heating at the magnet's suspension points which can prevent superconductive operation, as can be appreciated by those skilled in the art. Likewise, shock and vibration forces during magnet operation subject the superconductive coil to deflections within the vacuum enclosure leading to frictional heating at the magnet's suspension points which can cause the magnet to quench (i.e., lose its superconductivity). Known magnet supports employing tie rod straps or pedestal stands provide limited or no protection of the superconductive coil against deflections due to shock and vibration forces. What is needed is a cryocooler-cooled superconductive magnet with an improved magnet support structure.